Epoxide compositions containing a catalytic amount of a stannic organophosphate



United States Patent M 3 281 376 nroxmn coMrosrrrorss coN'rArNiNo A CATA- LYTIC AMOUNT OF A STANNIC ORGANQPHOS- PHATE William R. Proops, Charleston, W. Va, assiguor to Union Carbide Corporation, a corporation of New York No Drawing. Filed Dec. 29, 1961, Ser. No. 163,060

9 Claims. (Cl. 2602) Thisinvention relates to epoxide compositions and to the curing of certain epoxides with tetravalent tin catalysts.

A variety of catalysts have been suggested for use in promoting the cure or polymerization of epoxide compositions into hardened, infusible and insoluble products of relatively high molecular weight, the cured epoxy compound being either in the form of a homopolymer or copolymer with various organic compounds capable of interaction with the active groups of the epoxide. Included among the known catalysts are strongly acidic materials such as sulfuric acid, phosphoric acid, etc.; aromatic sulfonic acids such as toluenesulfonic acid and benzenesulfonic acid; Lewis acids, e.g., boron trifluoride, stannic chloride, etc.; and boron trifluoride-amine complexes such as boron trifluoride-monoethylamine, boron trifluoridepiperidine, and the like. Although these catalysts are eifective for the curing or polymerization process, their use has been handicapped to some extent due to a number of reasons. For example, the use of Lewis acid catalysts such as boron trifluoride sulfer the disadvantage of effecting rapid and uncontrolled exotherms during the cure of epoxides to resins, frequently causing thermal decomposition in the composition as evidenced by eharring, or expulsion of components as indicated bybubble formation and foaming. A number of these catalysts are of a corrosive nature and cause uncontrollable gel rates in the cure of certain epoxide formulations which thus seriously limits their industrial application in the field of coatings, adhesives and potting compositions.

The present invention is based on the discovery that tetravalent tin compounds of the class of stannic organophosphates are especially effective catalysts for promoting the cure of epoxide compositions. It has been found that the incorporation of stannic organophosphates in epoxide compounds provides curable compositions which have a good working life and can be cured at room temperature without incurring rapid gelation or uncontrollable exotherms. The curable compositions can be spread, brushed or sprayed by techniques known in the paint, varnish and lacquer industries, and can be advantageously used in the encapsulation of electrical components. In one aspect, mixtures of stannic catalysts with epoxides containing the cyclohexene oxide or cyclopentene oxide group olfer a distinct advantage over epoxides of the polyglycidyl ether type inasmuch as they can be reacted with various hardeners and foamed by internal development of carbon dioxide or by a blowing agent which vaporizes at or below the temperature of the foaming mass to provide foamed polymers of widely varying and preselected properties. Foamed polymers of this type find wide utility in the field of structural reinforcement and insulation.

The stannic or anophosphates which are used may be represented by the formula:

in which R is a monovalent hydrocarbon radical, saturated or unsaturated, branched chain or straight chain, containing 1 to 18 carbon atoms, preferably 3 to 12. Representative examples of stannic organophosphates include stannic tetrakis [di (propyl)phosphate] stannic tetrakis [di(isopropyl) phosphate] 3,2833% Patented @ct. 25, 1966 stannic tetrakis[di (butyl)phosphate],

stannic tetrakis [di (pentyl) phosphate], stannic tetrakis[di (hexyl)phosphate] stannic tetrakis [di(2-ethylhexyl) phosphate] stannic tetrakis [di (heptyl)phosphate] stannic tetrakis [di (3 -ethylheptyl phosphate] stannic tetrakis [di (nonyl phosphate] stannic tetrakis [di(4-propylnonyl) phosphate] stannic tetrakis[di (dodecyl)phosphate] stannic tetrakis [di (tetrade cyl) phosphate], stannic tetrakis [di(octadecyl) phosphate] and the like.

The stannic catalysts may be substituted in the hydrocarbon radical with hydroxy, halo, keto, and similar groups.

The stannic organophosphates may be made by an exchange reaction of a stannic alkoxide, such as stannic t-amyloxide, with an organophosphoric acid to form the stannic organophosphate and the corresponding alcohol of the stannic alkoxide. The stannic alkoxides may be made by the method of D. C. Bradley, E. V. Caldwell and W. Wardlaw, J. Chem. Soc., 4775 (1957). Thus the aforementioned stannic organophosphates can be prepared by an exchange reaction of, for example, stannic t-amyloxide, with dipropylphosphoric acid, diisopropylphosphoric acid, dibutylphosphoric acid, dipentylphosphoric acid, dihexylphosphoric acid, di(2-ethylhexyl) phosphoric acid, diheptylphosphoric acid, di(3- ethylheptyl) phosphoric acid, dinonylphosphoric acid, di(4-propylnonyl)phosphoric acid, clidodecyl-phosphoric acid, di(tetradecyl) phosphoric acid, dioctadecyl phosphoric acid and the like.

In a preferred embodiment, the catalysts of the instant invention are prepared by forming a mixture of toluene and the organophosphoric acid and distilling off a portion of the mixture to insure the removal of water. Thereafter, the stannic t-amyloxi-de is added and the mixture heated to approximately 112 C. for about 20 minutes. The toluene and tsamyl alcohol formed are than distilled off, leaving the stannic organophosphate as a residue.

In carrying out the invention, the stannic catalysts are mixed with epoxides to obtain a homogeneous curable composition. With epoxides that are liquid and viscous, the catalyst can be simply admixed with the epoxide by conventional means as, for example, by stirrers and impellers, etc. When the catalyst and epoxide are immiscible at room temperatures, or if the epoxide is normally solid, the epoxide can be melted or mixed with a liquid organic solvent. Typical solvents includes organic ethers such as diethyl ether, methyl propyl ether, etc.; organic esters such as methyl acetate, ethyl propionate, etc.; and organic ketones such as acetone and cyclohexanone, etc.

The amount of catalyst employed will vary with the cure rate desired and the curing temperature employed. As a general guide, good results are obtained by utilizing the stannic catalyst in amounts ranging between 0.001 and 20 percent, preferably 0.1 to 10 percent by weight based on the total weight of the curable epoxide composition.

The mixture of epoxide composition and catalyst can be cured over a wide temperature range. For example, the catalyst can be added to the epoxide composition at room temperatures, i.e., about 15 C. to 25 C., and the cure effected, or if a rapid cure is desired the mixture can be heated to temperatures as high as 250 C. or more. Higher temperatures above 250 C. are generally undesirable due to the discoloration which may be induced. Other single curing temperatures and combinations of curing temperatures can be employed as desired.

The stannic catalysts described above are used to promote the cure of a Wide variety of known monoepoxide and polyepoxide compositions, the cured composition produced being in the form of a homopolymer, or copolymer with an active organic hardener. The curable epoxide compositions can be monomeric or polymeric, saturated or unsaturated, aliphatic, aromatic or heterocyclic, and can be substituted, if desired, with substituents such as hydroxy, halide, alkyl, aryl, carboxyl, and the like. Thus, for example, the instant invention contemplates the preparation of homopolymers and copolymers of mono epoxides and polyepoxides containing cyclohexene oxide, cyclopentene oxide, bicycloheptene oxide, and cyclooctene oxide groups. Also included are the epoxidized alkenes, the glycidyl ethers of polyhydric phenols and alcohols, epoxidized polybutadiene, epoxidized copolymers of butadiene, epoxidized natural oils, and the like.

In one embodiment of the instant invention the mono meri-c polyepoxides which can be cured with the stannic catalysts contain at least two oxirane oxygen atoms, at least one of which is bonded to two vicinal cycloaliphatic carbon atoms. The other oxygen atom is also bonded to two vicinal carbon atoms, but the carbon atoms need not necessarily form part of a cycloaliphatic ring. Thus, the polyepoxide component contains at least two vicinal epoxy groups, i.e.,

the epoxy carbon atoms of at least one of the groups forming a portion of a cycloaliphatic hydrocarbon nucleus. The cycloaliphatic nucleus preferably contains from 4 to 8 carbon atoms including the epoxy carbon atoms, and preferably from 5 to 7 carbon atoms.

Diepoxides which contain both oxirane oxygen atoms bonded to cycloaliphatic carbon atoms are highly preferred. Polyepoxides which contain solely carbon, hydrogen, and oxygen atoms are especially preferred. The oxygen atoms can be (in addition to oxirane oxygen) etheric oxygen, i.e., O; oxygen present in an ester group, i.e.,

oxygen present in a carbonyl group, i.e.,

o g and the like. A single polyepoxide or a mixture of at least two polyepoxides can be employed in the novel curable compositions.

Illustrative polyepoxides include, for example, the alkanediol bis(3,4-epoxycyclohexanecarboxylates), the alkenediol bis(3,4-epoxycyclohexanecarboxylates), the alkanediol bis(lower alkyl substituted-3,4-epoxycyclohexanecarboxylates), the oxaalkanediol bis(lower alkyl substituted 3,4 epoxycyclohexanecarboxylates), the alkanetriol tris(3,4-epoxycyclohexanecarboxylates), the alkenetriol tris(3,4-epoxycyclohexanecarboxylates), the alkanetriol tris(lower alkyl substituted-3,4-epoxycyclohexanecarboxylates), the oxaalkanetriol tris(3,4-epoxycyclohexanecarboxylates), the oxaalkanetriol tris(lower alkyl substituted 3,4 epoxycyclohexanecarboxylates), and the like. The above-illustrated polyol poly(3,4-epoxycyclohexanecarboxylates) can be prepared by epoxidizing the corresponding polyol poly(cyclohexenecarboxylate) with at least a stoichiometric quantity of peracetic acid (preferably contained as solution in ethyl acetate) per carbon to carbon double bond of said polyol poly(cyclohexenecarboxylate), at a temperature in the range of from about 25 to 90 C., for a period of time sufficient to introduce oxirane oxygen at the sites of all the carbon to carbon double bonds contained in the polyol poly(cyclohexenecarboxylate) reagent. The polyol poly(cyclohexenecarboxylates), in turn, can be prepared in accordance with well known condensation techniques, e.g., the esterification of a polyol, e.g., ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, the polyoxyethylene glycols, 1,4-

butanediol, 1,5-pentanediol, 1,6-hexanediol, the octanediols, the octadecanediols, the butenediols, the pentenediols, the hexenediols, the octenediols, 1,2,3-propanetriol, trimethylolmethane, 1,1,1 trimethylolethane, 1,1,1 trimethylolpropane, 1,2,6-hexanetriol, cycloaliphatic triols, aromatic triols, and the like; with a 3-cyclohexenecarboxylic acid, e.g., 3-cyclohexenecarboxylic acid, lower alkyl substituted 3 cyclohexenecarboxylic acid, and the like. The expression lower alkyl, as used in the disclosure, means an alkyl radical which contains from 1 to 4 carbon atoms.

Other polyepoxides contemplated include, for instance, the bis(3,4-epoxycyclohexylmethyl) hydrocarbon dicarboxylates and the bis(lower alkyl substituted-3,4-epoxycyclohexylmethyl) hydrocarbon dicarboxylates, e.g., bis- (3,4-epoxycyclohexylmethyl) oxalate, bis( 3 ,4-epoxycyclohexylmethyl) malonate, bis 3 ,4-epoxycyclohexylmethyl) succinate, bis(3,4-epoxycyclohexylmethyl) glutarate, bis- (3,4-epoxycyclohexylmethyl) adipate, bis(3,4-epoxycyclohexylmethyl) maleate, bis(3,4 epoxycyclohexylmethyl) tetrahydrophthalate, bis(3,4 epoxycyclohexylmethyl) citraconate, bis(3,4-epoxycyclohexylmethyl) isocitraconate, bis(3,4-epoxy-6-methylcyclohexylmethyl) fumarate, bis- (3,4-epoxycyclohexylmethyl) pimelate, bis(3,4-epoxycyclohexylmethyl) terephthalate, bis(3,4-epoxycyclohexylmethyl) azelate, bis(3,4-epoxycyclohexylmethyl) sebacate, bis(3,4 -epoxycyclohexylmethyl) itaconate bis(3,4- epoxycyclohexylmethyl) hexahydrophthalate, bis(3,4-epoxycyclohexylmethyl) phthalate, bis(3 ,4-epoxycyclohexylmethyl) glutaconate, bis(3,4-epoxycyclohexylmethyl) hydromuconate, and the like.

Other desirable polyepoxides include the monoesters of 3,4-epoxycyclohexylmethanols and 3,4-epoxycyclohexanecarboxylic acids such as, for example, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, l-methyl-3,4- epoxycyclohexylmethyl 1 methyl-3,4-epoxycyclohexanecarboxylate, 6-methyl-3,4-epoxycyclohexylmethyl 6-methyl-3,4-epoxycyclohexanecarboxylate, 2 ethyl-3,4-epoxycyclohexylmethyl Z-ethyl 3,4 epoxycyclohexanecarboxylate, 4-n-propyl-3,4-epoxycyclohexylmethyl 4-n-propyl- 3,4-epoxycyclohexanecarboxylate, 5 isobutyl-3,4-epoxycyclohexylmethyl 5-isobutyl-3,4-epoxycyclohexanecarboxylate, lower alkyl substituted-3,4-epoxycyclohexylmethyl lower alkyl substituted-3,4-epoxycyclohexanecarboxylate, halo substituted-3,4-epoxycyclohexylmethyl halo substituted 3,4-epoxycyclohexanecarboxylate, 1-chloro-3,4-epoxycyclohexylmethyl 1 chloro-3,4-epoxycyclohexanecarboxylate, 2-brorno-3,4-epoxycyclohexylmethyl 2-bromo- 3,4-epoxycyclohexanecarboxylate, and the like.

Still other desirable polyepoxides include, by way of illustration, the

3-oxatehracyclo[4.4.0.1 ".0 ]undec-8-y1 vicinal-epoxyalkyl ethers,

the 3-oxatetracyclo [4.4.0.1 ".0 ]undec-8-yl vicinalepoxycycloalkylalkyl ethers,

the 3-oxatetracyclo[4.4.0.1 .0 ]undec-8-yl 3-oxatricyclo [3 .2.1.O ]oct-6-y1 ethers,

the 3-oxatetracyclo[4.4.0.1' .0 ]undec-8-yl 3-oxatricyclo[3.2.1.0 1oct-6-yl alkyl ethers,

and the like. Specific examples include 3-oxatetracyclo [4.4.0.1 .0 undec-B-yl 2,3-epoxypropyl ether,

3-oxatetracyclo[4.4.0.1 .0 ]undec-8-yl 3,4-epoxybutyl ether,

3-oxatetracyclo[4.4.0.1 ".0 ]undec-8-yl 2,3-epoxybutyl ether,

3oxatetra cyclo [4.4.0.1 .0 ]undec-8-y1 3,4-epoxyhexyl ether,

3-oxatetracyclo[4.4.0.1 .0 ]undec-8-yl 5,6-epoxyhexyl ether,

3-oxatetracyclo[4.4.0.1 .0 ]undec-8-yl 7,8-epoxyoctyl ether,

3-oxatetracyclo [4.4.0.1 ".0 ]undec-8-yl 2-methyl-2,3-

epoxypropyl ether,

3-oxatetracyclo[4.4.0.1 .0 ]undec-8-yl 2-ethyl-2,3-

epoxyhexyl ether,

3-oxatetracyclo[4.4.0.1 .0 ]undec-S-yl 9,10-epoxystearyl ether,

3-oxatetracyclo[4.4.0.1 .0 ]undec-8-yl 9,10,12,13-

diepoxystearyl ether,

3-oxatetracyclo[4.4.0.1 .0 ]undec-8-yl 2,3-epoxycyclopentyl ether,

3-oxatetracyclo[4-.4.0.1 .0 ]undec-8-yl 2,3-epoxycyclopentylmethyl ether,

3-oxatetracyclo [4.4.0.1 .O ]undec-8-yl alkyl substituted 3,4-epoxycyclohexyl ether,

3-oxatetracyclo[4.4.0.l' .0 ]undec-8-yl 3,4-epoxycyclohexyl ether,

3-oxatetracyclo[4.4.0.1 .0 ]undec-8-yl 2,3-epoxycyclohexyl ether,

3-oxatetracyclo [4.4.0.1 .0 ]undec-8-yl 3,4-epoxycyclohexylmethyl ether,

3-oxatetracyclo [4.4.0.1' .0 ]undec-8-yl 6-methyl-3,4-

epoxycyclohexylmethyl ether,

3-oxatetracyclo [4.4.0.l .-O ]undec-8-yl 5-methyl-3,4-

epoxycyclohexylmethyl ether,

3-oxatetracyclo[4.4.0.1 .0 ]undec-8-yl alkyl substituted 3-oxatricyclo [3 .2. 1 .0 oct-6-yl ether,

3-oxatetracyclo [4401 ]undec-S-yl 3-oxatricyclo- [3.2.1.0 ]oct-6-yl ether, and the like.

Examples of other monomeric polyepoxides, include l,4 bis(2,3-epoxypropoxy) benzene, 1,3-bis(2,3-epoxypropoxy)benzene, 4,4'bis(2,3-epoxypropoxy)diphenyl ether, 1,8-bis(2,3-epoxypropoxy)octane, 1,4bis 2,3 -epoxyprop oxy) cyclohexane, 4,4'-bis(2-hydroxy-3,4-epoxybutoxy)diphenyl dimethylmethane, 1,3-bis (4,5 -epoxypentoxy) -chlorobenzene, 1,4-bis (3 ,4-epoxybutoxy)-Z-chlorocyclohexane, 1,3-bis(2-hydroxy-3,4-epoxybutoxy)benzene, 1,4-bis 2-hydroxy-4,S-epoxypentoxy benzene.

Examples of vic-epoxyhydrocarbyl substituted aromatic hydrocarbons and halo-substituted aromatic hydrocarbons include, among others, 1,4-bis(2,3-epoxypropyl)benzene, 1,4-bis(2,3-epoxycyclohexyl)benzene, l,4-bis 2,3-ep oxy-butyl )benzene, 1,3 bis(2,3-epoxypropyl)benzene,

1,4-bis(2,3-epoxyhexyl)benzene,

and preferably, a plurality of vicinal epoxy groups. These epoxidized polymers can be prepared -by the epoxi-dation of the corresponding olefinically unsaturated polymer precursor which has an average molecular weight in the range of from about 250 to about 250,000, and higher, preferably from about 250 to about 25,000, and preferably still, from about 500 to about 10,000. The term average is to be noted since the individual molecules of a given sample of olefinically unsaturated polymeric product which result from the polymerization reaction of the appropriate monomeric reagent(s), in general, vary in molecular weight (or degree of polymerization). Consequently, the overall molecular weight of the sample is the average of the molecular weight of the individual poly: meric molecules which comprise said sample.

In a broad aspect, the epoxidized polymers which are contemplated include, among others, the partially to essentially completely epoxidized polymers of conjugated dienes; the partially to essentially completely epoxidized copolymers of conjugated dienes with olefinic monomers; and the like. The term polymer, as employed herein including the appended claims, is used in its generic sense to encompass homopolymers and copolymers. It is pointed out, also, that the term partially to essentially completely epoxidized (polymers or copolymers) means that the epoxidized polymers which are useful in the invention can range from those which contain, on the average, at least one single vicinal epoxy group and, on the average, a plurality of ethylenic groups to those which contain, on the average, a plurality of vicinal epoxy groups and relatively few, or none, ethylenic groups. As a practical matter, especially from a commercial standpoint, it is somewhat difiicult and expensive to fully and completely epoxidize the olefinically unsaturated polymer precursor.

In one aspect, the epoxidized polymers which are contemplated as a component(s) in the novel curable compositions contain at least one percent oxirane oxygen to below about 23 percent oxirane oxygen, and preferably, from about 3 to about 12 percent oxirane oxygen. The term percent oxirane oxygen designates the number of grams of oxirane oxygen per grams of a sample of epoxidized polymer. The upper limit regarding the percent oxirane oxygen is a variable which will depend upon the average molecular weight of the olefinically unsaturated polymer precursor, the degree of epoxidation of the olefinically unsaturated polymer precursor, the monomers employed to prepare said precursor, the degree and number of side reactions which can occur during the epoxidation reaction other than that of introducing oxirane oxygen at the site of the ethylenic carbon to carbon double bond of said precursor, and the like. Nevertheless, the invention contemplates the use of essentially completely epoxidized polymers, and consequently, the determination of the upper limit of percent oxirane oxygen is readily determined Via ordinary experimentation by a chemist. However, it must be borne in mind that with regard to the upper limit of percent oxirane oxygen, this limit is a Variable governed by practical and readily determined factors such as those illustrated above.

The conjugated dienic monomers which are useful in preparing the non-epoxidized polymers, i.e., the olefinically unsaturated polymer precursors, are characterized by the whereas the olefinic monomers are characterized by at least one unit. It is apparent, therefore, that the olefinic monomer can contain more than one taining the unit,

.4 z l \i 1 i3 iv (of the unit l=-( l= However, the presence of negative groups on the ethylenic carbon atoms of polymers which result from the 1,4-addition route tends to inactivate the ethylenic group toward epoxidation, i.e., the introduction of oxirane oxygen at the site of the resulting carbon to carbon double bond is difficult when negative groups are attached to the ethylenic carbon atoms of the polymer.

Specific illustrative conjugated dienic monomers which are useful in the preparation of the non-epoxidized polymers include, for example, 1,3-butadine, 1-methy1-l,3-

. butadiene, 2-methyl-1,3-butadiene, 2-ethyl-1,3-butadiene,

l,1-dimethy1-1,3-butadiene, l,4-dimethyl 1,3 butadiene, 2,3-dimethyl-1,3-butadiene, 2-isopropyl-1,3-buta-diene, ln-propyl-1,3-butadiene, l-phenyl-l,3-butadiene, l-ethoxy- 1,3-butadiene, 1-acetoxy-l,3-butadiene, 1-allyl-1,3-butadiene, 2-methy1-6-methylene-2,7-octadiene, and the like. Conjugated dienic hydrocarbon monomers which contain from 4 to 8 carbon atoms are preferred in the preparation of the non-epoxidized homopolymers and copolymers. Conjugated butadiene is most preferred.

Exemplary olefinic monomers which are useful in the preparation of the non-epoxidized copolymers include, for instance, ethylene, propylene, isobutylene, butene-l, styrene, vinyltoluene, isopropenylbenzene, 4-vinylcyclohexene, divinylbenzene, vinyl chloride, allyl chloride, alpha-methylstyrene, alpha-chlorostyrene, 2,5 -dichlorostyrene, 4 cyanostyrene, 2 hydroxystyrene, 2 acetoxystyrene, chlorotrifluoroethylene, vinylidene chloride, vinyl fluoride, vinylidene fluoride, vinyl bromide, methyl acrylate, methyl methacrylate, ethyl methacrylate, octyl methacrylate, methyl crotonate, butyl crotonate, ethyl crotonate, dimethyl maleate, dibutyl maleate, dioctyl maleate, diethyl chloromaleate, diethyl fumarate, vinyl acetate, vinyl butyrate, vinyl Z-ethylhexanoate, vinyl stearate, vinyl oleate, vinyl linoleate, vinyl benzoate, vinyl crotonate, allyl acetate, acrylonitrile, methylacrylonitrile, acrylamide, methacrylamide, crotonamide, N-vinylbenzamide, N-vinylbutyramide, methyl vinyl ketone, methyl isopropenyl ketone, acrolein, vinyl ethyl ether, vinyl butyl ether, 2-vinylpyridine, N-vinyl carbazole, and the like. Preferred olefinic monomers include the alkenes, the phenyl substitutedalkenes, the olefinically unsaturated organic esters, the olefinically unsaturated amides, the olefinically unsaturated nitriles, and the like. Styrene, the lower alkyl acrylates, and the alkenes which contain up to carbon atoms are most preferred.

The preparation of the non-epoxidized homopolymers and copolymers is well documented in the literature. For example, US. Patents 2,500,933, 2,586,594 and 2,631,175 are illustrative of the reagents and modes for preparing various non-epoxidized polymers. Liquid polybutadiene which has an average molecular weight of at least 250 is highly preferred.

The preparation of the epoxidized polymers which are employed as a component(s) in the novel curable, polymerizable compositions can be accomplished by epoxidizing the corresponding olefinically unsaturated homopolymer or copolymer precursors such as those exemplified previously with well known epoxidizing agents, and preferably with organic peracids. Since the epoxidation reaction is carried out in a liquid phase, practical considerations are readily suggested to the chemist skilled in the epoxy art. Thus, if the olefinically unsaturated homopolymer or copolymer precursor is a liquid, then an inert normally liquid organic solvent is not essential, though one can be employed if desired. However, if the unsaturated homopolymer or copolymer precursor is a solid, then said solid precursor should be soluble in an inert normally liquid organic vehicle in order for it to undergo effective epoxidation. Inert organic vehicles such as chloroform, toluene, benzene, ethylbenzene, xylene, acetone, methyl ethyl ketone, butyl acetone, ethyl acetate, and the like, are illustrative of the common solvents which may be employed. The particular homopolymer or copolymer precursor, its degree of polymerization, i.e., its

average molecular weight, its preparation, and other factors, will influence, to a large extent, the solubility of said precursor in any given inert normally liquid organic vehicle. It is readily recognized by polymer chemists that many highly polymerized compounds are solids of extremely limited solubility in otherwise useful inert organic media, and in this respect, a practical upper limit is imposed on the degree of polymerization of the olefinically unsaturated homopolymer or copolymer precursor. Thus, the solid non-epoxidized olefinically unsaturated polymers which are contemplated are soluble in an inert normally liquid vehicle, the choice of said inert normally liquid vehicle being readily determined by the merest of routine experimentation by the artisan in the epoxy art.

Other useful polyepoxides include epoxides derived from natural oils, such as linseed oil epoxide, soybean oil epoxide, safilower oil epoxide, tung oil epoxide, castor oil epoxide, lard oil epoxide, and the like, which are glycerides containing 45 to carbon atoms.

The stannic catalysts of the instant invention can also be employed to cure monoepoxides, i.e., compounds containing only one vicinal epoxy group, which may be present as part of a cycloaliphatic nucleus or part of an aliphatic chain. Typical monoepoxide compounds include ethylene oxide, propylene oxide, 1,2-epoxyoctane, cyclohexene oxide, 1,2-epoxypropyl benzene, and the like.

It should be noted that the aforementioned epoxides are given only for purposes of illustrating the wide variety of monoepoxides and polyepoxides which can be cured by the catalysts of the instant invention and n0 unnecessary limitations are to be inferred therefrom.

The epoxides with the stannic catalyst of the type illustrated above can be homopolymerized or copolymerized with an active organic hardener of combination of active organic hardeners. By the term active organic hardener, as used herein, is meant an organic compound which contains two or more groups which are reactive with epoxy groups. The active organic hardeners illustrated hereinafter are employed in a curing amount, that is, an amount which is sufiicient to cause the epoxide system containing the active organic.hardencr(s) to become polymerized. The active organic hardeners can also be employed in varying amounts so as to give a wide variety of properties to the cured epoxide system. Typical groups which are reactive with epoxy groups are active hydrogen groups suchv as hydroxyl groups, carboxyl groups, amino groups, thiol groups, and the like; and isocyanate groups, isothiocyanate groups, halide atoms of acyl halides, and the like. Oxydicarbonyl groups such as those contained by polycarboxylic acid anhydrides are also active with epoxy groups. One oxydicarbonyl group will react with two epoxy groups and, in this connection, polycarboxylic acid anhydrides need only contain one oxydicarbonyl group in order to function as an active organic hardener with the epoxide compositions of this invention. Stated differently, one oxydicarbonyl group of an anhydride is equivalent to two epoxy-reactive groups.

Representative active organic hardeners include polyfunctional amines, polycarboxylic acid, polycarboxylic acid anhydrides, polyols, i.e., polyhydric phenols and polyhydric alcohols, polythiols, polyisocyanates, polythioisocyanates, polyacyl halides and others. By the term polyfunctional amine, as used herein, is meant an amine having at least two active amino hydrogen atoms which can be on the same nitrogen atom or different nitrogen atoms.

Resins having particularly valuable properties can be formed from mixtures containing the epoxide compositions and polyfunctional amines in such relative proportions as to provide from 0.2 to 5.0 amino hydrogens of the amine for each epoxy group contained by said epoxide composition. It is preferred to form resins from curable mixtures containing the epoxide compositions and polyfunctional amines which provide from 0.3 to 3.0 amino hydrogens for each epoxy group.

Among the polyfunctional amines contemplated as active organic hardeners include the aliphatic amines, aromatic amines, aralkyl amines, cycloaliphatic amines, alkaryl amines, aliphatic polyamines including polyalkylene polyamines, amino-substituted aliphatic alcohols and phenols, polyamides, addition products of polyamines and low molecular weight epoxides containing oxirane oxygen linked to vicinal carbon atoms, and others.

Typical aliphatic amines include mcthylamine, ethylamine, propy-lamine, isopropylamine, butylamine, isobutylamine, Z-ethylhexylamine, 3-propylheptylamine, and the like.

Examples of aromatic amines, aralkyl amines and alkaryl amines include, among others, aniline, o-hydroxyaniline, m-toluidine, 2,3-xylidine, benzylamine, phenethylamine, l-n-aphthylamine, meta-, orthoand paraphenylenediamines, 1,4-naphthalenediamine, 3,4-toluenediamine and the like.

Illustrative cycloaliphatic amines include cyclopentylamine, cyclohexylamine, p-methane-l,8-diamine and others.

Among the polyamides, i.e., those having an average molecular weight range from about 300 to about 10,000, include condensation products of polycarboxylic acids, in particular, hydrocarbon dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, dilinolenic acid, and the like, with polyamines, particularly diamines such as ethylenediamine, propylenediamine, and the like.

Aliphatic polyamines include ethylenediamine, propylenediamine, butylenediamine, pentylenediamine, hexylenediamine, octylenediamine, nonylenediamine, decylenediamine, and the like. Polyalkylene polyamines such as diethylenetriamine, triethylenetetramine, tetraethylpentamine, dipropylenetriamine, and the like, are particularly suitable.

The amino-substituted aliphatic alcohols and phenols suitable for use in the present invention are illustrated by Z-aminoethanol, Z-aminopropanol, 3-amin0butanol, 1,3- diamino-Z-propanol, 2-aminophenyl, 4-aminophenyl, 2,3- diaminoxylenol, and the like.

Other illustrations of polyfunctional amines are the addition products of polyamines, in particular, diamines and triamines and epoxides containing oxirane oxygen linked to vicinal carbon atoms such as ethylene oxide, propylene oxide, butadiene dioxide, diglycidyl ether, epox-idized soybean oil, epoxidized saffiower oil, and polyglycidyl polyethers such as those prepared from polyhydric phenols and epichlorohydrin. Particularly useful polyfunctional amines are the monoand polyhydroxyalkyl polyalkylene and arylene polyamines which can be prepared by the addition reaction of polyalkylene polyamines, arylene polyamines, and the like, e.g., ethylenediamine, propylened-iamine, diethylenetriamine, hexamethylenediamine, triethylenetetramine, tetraethylenepentamine, phenylenediamine, methylenedianiline, xylenediamine, and the like, with ethylene oxide or propylene oxide such that the resulting amine adduct contains two or more active hydrogen atoms attached to either one or more amino nitrogen atoms.

Examples of still other polyfunctional amines suitably adaptable include, among others, heterocyclic nitrogen compounds such as piperazine, 2,5-dimethylpiperazine, and the like; aminoalkyl-substituted heterocyclic com pounds such as N(aminopr-opyl)morpholine, N-(aminoethyl)morpholine, and the like; amino-substituted hetero-' cyclic nitrogen compounds such as melamine, 2,4-diamino- 6-(aminoethyl) pyrimidine, and the like; dimethylurea, guanidine, p,p'-sulfonyldianiline, 3,9-bis(aminoethyl)- spirobimetadioxane, hexahydrobenzamide, and others.

Other polyfunctional amines having a total of at least two active amino hydrogen atoms to the molecule can be employed in the epoxide compositions of this invention.

For example, such polyfunctional amines as mixtures of p,p'-methy1enedianiline and m-phenylenediamine, or other mixtures of two or more polyfunctional amines can be used.

Another class of active organic hardeners which can be reacted with the epoxide compositions above, are the polycarboxylic acids. By the term polycarboxylic acid, as used herein, is meant a compound or polymer having two or more carboxyl groups to the molecule. Curable mixtures can be formed from the epoxide compositions and polycarboxylic acids, which mixtures. can be cured to produce a wide variety of useful products. Valuable resins can be made from mixtures containing such amounts of an epoxide composition and polycarboxylic acid as to provide 0.3 to 1.25 carboxyl groups of the acid for each epoxy group contained by the amount of the epoxide composition. It is preferred, however, to make resins from curable mixtures which contain such amounts of polycarboxylic acids and epoxide compositions as to provide 03 to 1.0 carboxyl groups of the acid for each epoxy group from the epoxide composition.

Representative polycarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, alkylsuccinic acids, alkenylsuccinic acids, ethylbutenylsuccinic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid, ethylidenemalonic acid, isopropylidenemalonic acid, allylmalonic acid, muconic acid, alphahydromuconic acid, beta-hydromuconic acid, diglycollic acid, dilactic acid, thiodiglycollic acid, 4- amyl-2,5-heptadienedioic acid, 3-hexynedioic acid, 1,2- cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylio acid, 2-carboxy-2-methylcyclohexaneacetic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, tetrachlorophthalic acid, l,8-naphthalenedicarboxylic acid, 3-carboxycinnamic acid, 1,Z-naphthalenedicarboxylic acid, 1,1,5-pentanetricarboxylic acid, 1,2,4-hexanetricarboxylic acid, Z-propyl-l,2,4-pentanetricarboxylic acid, 5- octene-3,3,6-tricarboxylic acid, 1,2,3-propanetricarboxylic acid, l,2,4-benzenetricarboxylic acid, 1,3,5-benzenetricarboxylic acid, 3hexene-2,2,3,4-tetracarboxylic acid, l,2,3,4- benzenetetracarboxylic acid, 1,2,3,S-benzenetrctracarboxylic acid, benzenepentacarboxylic acid, benzenehexacarboxylic acid, polymerized fatty acids derived from natural oils, e.g., linseed oil, tung oil, soybean oil, dehydrated castor oil, etc, including mixtures thereof, which have a molecular weight within the range of 500 to 5000, and the like, such as the dime-r and trimer acids of commerce.

Also, as polycarboxylic acids useful in the polyme-rizable compositions there are included compounds containing ester groups in addition to two or more carboxy groups which can be termed polycarboxy polyesters of polycarboxylic acids, such as those listed above, or the correspond ing anhydrides of said acids, esterified with polyhydric alcohols. Stated in other words, by the term polycarboxy polyesters, as used herein, is meant polyesters containing two or more carboxy groups per molecule. These polycarboxy polyesters can be prepared by known condensation procedures, employing mol ratios favoring greater than equivalent amounts of p-olycarboxylic acid, or anhydride. More specifically, the amount of polycarboxylic acid, or anhyd ride, employed in the esterification reaction should contain more carboxy groups than are required to react with the hydroxyl groups of the amount of polyhydric reactant.

Polyhydric alcohols which can be employed in preparing these polycarboxy polyesters include dihydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylcne glycols, tripropylene glycols, polyoxyethylene glycols, polyoxypropylene glycols, 1,2-butylene glycol, 1,4-butylene glycol, pentanc-l,5-diol, pentane- 2,4-diol, 2,2-dimethyltrimethylene glycol, hexane-1,4-diol, hexane-1,5-diol, hexane-1,6-diol, hexane-2,5-diol, Z-metbylpentane-l,5-diol, Z-methylpentane-2,5-diol, 3-methylpen- 11 tane-2,5-diol, 2,2-diethylpropane-l,3-dil, 2,2-diethylhexane-l,3-diol, 2,5-dimethylhexane-2,S-diol, octadecane-1,12 diol, l-butene-3,4-diol, 2-butene-l,4-diol, 2-butyne-1,4-dio1, 2,5-dimethyl-3-hexyne-2,5-diol and the like; trihydric al- 12 thalic acid, terephthalic acid, isophthalic acid and the like. Also, other dicarboxylic acid anhydrides, useful in our polymerizable compositions include the Diels-Alder adducts of maleic acid and alicyclic compounds having concohols such as glycerol, trimethylolethane, hexane-1,2,6- 5 jugated double bonds, e.g., methylbicyclo-[2.2.1]heptenetriol, 1,1,l-trimethylolpropane, and the ethylene oxide and 2,3-dicarboxylic anhydride. propylene oxide adducts thereof; tetrahydric compounds Thermoset resins can be prepared from mixtures consuch as pentaerythritol, diglycerol and the like; and higher taining the epoxide compositions and polyols by providpolyhydric compounds such as pentaglycerol, dipentaeing 0.1 to 2.0, preferably from 0.2 to 1.5, hydroxyl groups ryt'hritol, polyvinyl alcohols and the like. Additionalpolyof the polyol for each epoxy group contained by the hydric alcohols useful in making polycarboxy polyesters amount of the epoxide composition. By the term polyol, can be prepared by the reaction of epoxides, e.g., diglycidyl as used herein, is meant an organic compound having at diethers of 2,2-propane bisphenol, and reactive hydrogenleast two hydroxyl groups which are alcoholic hydroxyl containing organic compounds, e.g., amines, polycarboxgroups, phenolic hydroxyl groups, or both alcoholic and ylic acids, polyhydric compounds and the like. In formphenolic hydroxyl groups. The epoxide composition and ing the polycarboxy polyesters, it is preferable to use a polyol can be mixed in any convenient manner. A predihydric, trihydric or tetrahydric aliphatic or oxaaliphatic ferred method, however, is to mix the polyol and epoxide alcohol. The mol ratios in which the polycarboxylic acid composition in the liquid state so as to obtain a uniform or anhydride can be reacted with polyhydric alcohols in mixture. In forming this mixture, it may be necessary to preparing polycarboxylic polyesters useful in the composiraise the temperature of the polyol and epoxide compositions are those which provide polyesters having more than tion to at least the melting point or melting point range one carboxy group per molecule. of the highest melting component. Temperatures below Curable mixtures containing the epoxide compositions abou 150 C. are preferred so as to avoid possible preand polycarboxylic acid anhydrides can also be employed mature curing of these curable mixtures. Stirring also to produce resins having diversified and valuable propaids the formation of a homogeneous mixture. erties. Particularly valuable resins can be made from Representative polyols include ethylene glycol, diethylmixture containing such amounts of polycarboxylic acid ene glycol, polyethylene glycols, propylene glycol, dianhydride and epoxide compositions as to provide 0.2 to propylene glycol, polypropylene glycols, trimethylene 3.0 carboxy equivalent of the anhydride for each epoxy glycols, butanediols, pentanediols, 12,13-tetracosanediol, group of the epoxide composition. It is preferred, howglycerol, p yg y p ry i l, sorbitol, p ly y ever, to make resins from curable mixtures which contain alcohols, cyclohexanediols, inositol, dihydroxytoluenes, such amounts of polycarboxylic acid anhydride and epoxresorcinol, catechol, bis(4-hydroxyphenyl)-2,2-propane, ide composition as to provide 0.4 to 2.0 carboxy equivalent Y yP Y and the ethylene and P of anhydride for each epoxy group contained by the pylene oxide adducts thereof, etc. amount of epoxide concentration. The following examples illustrate the best mode now Typical polycarboxylic acid anhydrides include succontemplated for 'y out the invention! cinic anhydride, glutaric anhydride, propylsuccinic anhydride, methylbutylsuccinic anhydride, hexylsuccinic EXAMPLES 144 anhydride, heptylsuccinic anhydride, pentenylsuccinic In the following examples, various proportions of 3,4- anhydride, octenylsuccinic anhydride, nonenylsuccinic 4O epoxy 6 methylcyclohexylmethyl 3,4-epoxy-6-methylanhydride, alpha, beta-diethylsuccinic anhydride, maleic cyclohexanecarboxylate were mixed with stannic tetrakis anhydride, chloromaleic anhydride, dichlorornaleic an- [di(2-ethylhexyl)phosphate] catalyst and various active hydride, itaconic anhydride, eitraconic anhydride, hexaorganic hardeners. hydrophthalic anhydride, hexachlorphthalic anhydride, The proced re for testing the stannic organophosphates tetrahydrophthalic anhydride, methyltetrahydrophthalic with the epoxide and various hardeners, as summarized in anhydride, tetrachlorphthalic anhydride; hexachloroendo- Table I, was as follows: In general, the epoxide and hardmethylenetetrahydrophthalic anhydride, otherwise known ener were mixed at room temperature, warmed to the as chlorendic anhydride, tetrabromophthalic anhydride, minimum temperature necessary for solution to occur and tetraiodophthalic anhydride; phthalic anhydride, 4-nitrocatalyst added. After bringing the contents of the tubes phthalic anhydride, 1,2-naphthalic anhydride; polymeric to 150 C., the tubes were closed and placed in the oven dicarboxylic acid anhydrides, or mixed polymeric dicarat this temperature. In every case, the catalysts caused boxylic acid anhydrides such as those prepared by the the liquid mixtures to gel much more rapidly and produce autocondensation of dicarboxylic acids, for examples, harder resins than the controls. Even in those cases adipic acid, pimelic acid, sebacic acid, hexahydroisophwhere gels at 150 C. were not observed, use of catalysts TABLE I Hardener Stannic Tetra- Example Epoxidep kis [di(2-ethyl- Ratio Gel Time at Barcol b Remarks No. gms. hexyDphos- 150 0.

Name Gms phate], gms.

1,2,6-hexanetriol 0. 23 1:0. 5 Vi c liq, at temp do 110.5 0.23 110.5 120.5

110.5 1. 5-1. hrs--. 0 Brlttle. 0.23 110.5 5-8mins.-. 0 110.5 6-22 hrs 0 0. 23 Viscous liquid at rm. temp. (More 1V4i)seous than Ex- 14 23 Vi s o s liqiiid at rm. temp,

8 Ratio of epoxide to reactive or functional group. Barcol Impressor GYZJ934-1 was used to determine Bar-('01 N o.

d Methylbieyclo-[2.2.1]heptene-2,3-diearboxylie anhydride.

Emery Empol 1022 Dimer Acid; 578 mol. wt. neutralization equivalent=300.

13 gave much thicker liquids at room temperature. In all experiments, 0.23 gram of stannic tetrakis[di(2-ethylhexyl)phosphate] was used (equivalent to 1 percent since the total resin charge was about 23 grams). Unless other- 1 4 EXAMPLE 43 Preparation of stzmnic tetrakis[di(2-ethylhexyl) phosphate] To a 1 liter flask equipped with a 1 inch by 3 foot wise indicated all resins were cured for 22 hours at 150 C. 5 colurfm were added 500 gTaIPS oftohlene 72 grams EXAMPLES 28 of d1(2-ethylhexyl)phosphorlc acld. The mixture was heated and approximately 75 millimeters taken off over- The following examples demonstrate the effectiveness of head to remove traces of water. Thereafter grams of the stannic organophosphate catalysts for the homopolymstanni c t-amyloxide were added to the mixture which was erization of the diglycidyl ether of bisphenol A and its 10 maintained at about 112 C. After approximately 22 copolymerization with various hardeners. The catalyst minutes toluene and t-amyl alcohol were distilled off as was added to a homogenous solution as before and the a constant boiling mixture. The residue was refluxed for curing was performed at the temperature and for the 2 hours at 150 C. and at a pressure of 1 millimeter of periods indicated; the results being given in Table II. mercury, whereupon 76 grams of st-annic tetrakis[di(2- TABLE II Hardoner Stannie tetra- 150 0. Example Epoxide, kis[di(2'ethyl- Ratio 8 Gel time, at cure, Bareol b Remarks No. gms. hexyDphos- 150 Hrs.

Name Gms pllate], girls.

20 1,2,6-hexanetriol 2. 34 23 1:0. 5 6-22 hrs 22 0 20 do 2. 34 1:0. 5 22 Liquid at rm.

temp.

15. 7 Methyl nadie anhydride 7. 3 .23 11 3.75-4 hrs. 22 33 15.7 .do 7.3 1:1 622hrs 22 0 18.2 Tolylenediisocyanate 4.12 .23 110.5 2.75-3 hrs. 22 33 18.2 do 4.12 110.5 6-22 hrs.. 22 0 17. 73 4,4-diaminodiphenyl 4. 61 .23 1:1 8-18 mins. 22 Turbid resin.

17.73 d0 4.61 1:1 22-321mm. 22 ar.

12.8 Dimer acid K 10.2 23 1:0. 5 33-38 mins. 22 0 Hard rubbery 10.2 resin.

12.8 Dimer acid- 1:05 6-22 hrs. 22 0 Soft rubbery resin at room temp.

19.1 BisphenolA 5.6 .23 110.5 6-22 hrs. at 150 22 17 Brittle.

19.1 d 1:0.5 6-22 hrs. at 150.- 22 0 Very Brittle.

23 No gel 22 Tacky hard grease at room temp.

23 .do 22 Viscous liq. at

rm. temp.

2 Ratio of epoxide to reactive or functional group.

b Bargol Impressor GYZJ934-1 was used to determine Barcol N 0. a 70 Diglycidyl ether of bisphenol A. Methy1bicyclo-[2.2.1]heptene-2,3-dicarboxylie acid anhydride.

2 Emery Empol 1022 Dimer acid; 578 mol. wt., neutralization equivalent=300.

EXAMPLES 29-42 ethylhexyl)phosphate], a brown viscous liquid, were obtained. Analysis of the liquid indicated the following: Calculated for stannic tetrakis[di(2-ethy lhexyl)phosphate]: Sn, 8.3; C, 55.49; H, 9.59; P, 8.67. Found: Sn, 8.6; C, 54.01; H, 9.64; P, 5.36.

In a similar manner other stannic organophosphates can be prepared by an exchange reaction of stannic t-amyloxide with diisopropyl phosphoric acid, dibutylphosphoric acid, dipentylphosphoric acid, dihexylphoshours at 150 C. phone acid and the like.

TABLE III Stannic Example Methyl Nadic tetrakis[di(2- N o. Epoxide d Gms. Anhydrideg ethylhexyl)- Gel time, at; 150 C. Barcol b Remarks gms. phosphate],

gms.

11.7 11. 7 0.23 7-22 hrs Hard rubbery resin.

11.7 11.7 Viscous liq. at rm. temp.

10.1 12. 9 0.23 5-7 mins.'= 5 Added cat. at rm. temp.

Heated slowly. Controlled exotherm by cooling.

10. 1 12.9 1 5-2.5 hrs 31 11 12 0.23 Grease. Thicker than Example 34.

16. 7 6. 3 0.23 7-11 Inins 27 16.7 6. 3 6-22 hrs. 0

17. 7 5. 3 0.23 7-22 hrs Rubbery resin.

17.7 5.3 Viscous liq. at rm. temp.

16. 8 6. 2 0. 23 -65 mius 16. 8 6. 2 2.75-3.75 hrs.-.

16. 3 6. 7 0. 23 131-191 mins 16. 3 6. 7 44.25 hrs Epoxide F=l,2,3-propanetriol tris-(3,4-epoxycyelollexanecarboxylate). Epoxide G=1,1,1-trimethylolpr0pane tris-(8,4-ep0xycycl0hexanecarboxylate).

Although the invention has been illustrated by the preceding examples, it is not to be construed as limited to the materials employed therein, but rather, the invention encompasses the generic area as hereinbefore disclosed. Various modifications and embodiments of this invention can be made without departing from the spirit and scope thereof.

What is claimed is:

1. A curable composition comprising an epoxide compound containing at least one vicinal epoxy group and a catalytic amount of a stannic organophosphate compound of the formula:

atalpa] wherein R is an alkyl radical of from 1 to 18 carbon atoms.

2. A curable composition comprising an epoxide compound containing at least one vicinal epoxy group and a catalytic amount of stannic tetrakis[di(2-ethylhexyl)- phosphate].

3. A curable composition comprising an epoxide compound containing at least one vicinal epoxy group; an active organic hardener selected from the group consisting of polyamines, polycarboxylic acids, polycarboxylic acid anhydrides, polyols, polythiols, polyisocyanates, polyisothiocyanates and polyacyl halides; and a catalytic amount of a stannic organophosphate compound of the formula:

stat ng] wherein R is an alkyl radical of from 1 to 18 carbon atoms.

4. A curable composition comprising an epoxide compound containing at least one vicinal epoxy group; an active organic hardener selected from the group consisting of polyamines, polycarboxylic acids, polycarboxylic acid anhydrides, polyols, polythiols, polyisocyanates, polyisothiocyanates and polyacyl halides; and a catalytic amount of stannic tetrakis[di(2-ethylhexyl)phosphate].

5. A curable composition as claimed in claim 1 wherein the epoxide compound has at least one oxirane oxygen atom which is bonded to two vicinal carbon atoms of a cycloaliphatic ring structure containing from 5 to 7 carbon atoms.

6. In a process for curing epoxide compositions comprising an epoxide compound containing at least one vicinal epoxy group and a curing catalyst, the improvement which comprises using as the catalyst a stannic organophosphate compound of the formula:

Sn[Oi (OR)2]4 wherein each R is an alkyl group containing from 1 to 18 carbon atoms.

9. The process as claimed in claim 8 in which the catalyst is stannic 'tetrakis[di(2-ethylhexyl) phosphate].

References Cited by the Examiner UNITED STATES PATENTS 2,801,258 7/1957 Johnson 260-429.? 2,884,431 4/1959 Smith et al. 260-4299 2,885,415 5/1959 Ramsden 260-4297 2,916,473 12/1959 Bullock et al. 260-47 2,934,521 4/1960 Masters et al. 260-47 3,117,099 1/1964 Proops et al. 260-2 WILLIAM H. SHORT, Primary Examiner.

MILTON STERMAN, Examiner.

T. D. KERWIN, Assistant Examiner. 

1. A CURABLE COMPOSITION COMPRISING AN EPOXIDE COMPOUND CONTAINING AT LEAST ONE VICINAL EPOXY GROUP AND A CATALYSTIC AMOUNT OF A STANNIC ORGANOPHOSPHATE COMPOUND OF THE FORMULA: 